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Fencer Vulns
critical 9.8

CVE-2017-12240 kev in the critical feed json

The DHCP relay subsystem of Cisco IOS 12.2 through 15.6 and Cisco IOS XE Software contains a vulnerability that could allow an unauthentica…

published 2017-09-28 9 y ago modified 2026-06-17 4 mo ago also EUVD-2017-3813

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2022-03-03
epss
13.8%
EPSS 13.8% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

The DHCP relay subsystem of Cisco IOS 12.2 through 15.6 and Cisco IOS XE Software contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code and gain full control of an affected system. The attacker could also cause an affected system to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to a buffer overflow condition in the DHCP relay subsystem of the affected software. An attacker could exploit this vulnerability by sending a crafted DHCP Version 4 (DHCPv4) packet to an affected system. A successful exploit could allow the attacker to execute arbitrary code and gain full control of the affected system or cause the affected system to reload, resulting in a DoS condition. Cisco Bug IDs: CSCsm45390, CSCuw77959.

Patch / fix

cisa required action Apply updates per vendor instructions.

Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA patch deadline
  4. CISA SSVC: exploitation active

Known exploited

Added
4 y ago
Patch by
2022-03-24 (4 y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Cisco, IOS and IOS XE Software
CISA name
Cisco IOS and IOS XE Software DHCP Remote Code Execution Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
2 y ago

Exploit prediction

13.77% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a Cisco IOS and IOS XE

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.